Automatic grapple device

ABSTRACT

An automatic grapple for universal application including a support member having a loop for attachment to a hoist, a pair of crossed, barbed tongs pivoted to one another at their crossing point, links connecting one end of each of said tongs to said support member, a ram pivotally connected at one end to the pivot of said tongs, means on said support member defining a path for movement of said ram during closing and opening of said tongs, a trigger extending into said path to be struck by said ram, cooperating latching elements carried by said ram and support member for holding said tongs open, and link mechanism connecting said trigger to one of said latching elements and operative to move said one latching element into and out of latching engagement with the other latching element when actuated by movement of the trigger.

United States Patent [72] Inventors Adolph Anderson 238 39th Ave. 5.,West Richland; Donald R. Hodgin, 1316 Birch Ave.. Richland, both of,Wash. 99352 [2 l Appl. No. 850,410 [22] Filed Aug. 15, 1969 [45]Patented Aug. 3, 1971 [54] AUTOMATIC GRAPPLE DEVICE 12 Claims, 11Drawing Figs.

[52] 0.8. CI. 294/110, 294/ l 19 [5]] Int. CL. B25b 5/08 (50] Field olSearch 294/88, l06,ll0,ll8,ll9

[56] References Cited UNITED STATES PATENTS 2,629,627 2/1953 Stone294/110 2,776,l64 l/l957 Eckstein 2,894,782 7/1959 Puckettetal.

Primary Examiner-Even C. Blunk Assistant Examiner-Johnny D. CherryAttorney-Berman, Davidson and Berman ABSTRACT: An automatic grapple foruniversal application including a support member having a loop forattachment to a hoist, a pair of crossed, barbed tongs pivoted to oneanother at their crossing point, links connecting one end of each ofsaid tongs to said support member, a ram pivotally connected at one endto the pivot of said tongs, means on said support member defining a pathfor movement of said ram during closing and opening of said tongs, atrigger extending into said path to be struck by said ram, cooperatinglatching elements carried by said ram and support member for holdingsaid tongs open. and link mechanism connecting said trigger to one ofsaid latching elements and operative to move said one latching elementinto and out of latching engagement with the other latching element whenactuated by movement of the trigger.

AUTOMATIC GRAPPLE DEVICE This invention relates to an automatic grappledevice for universal application, and more particularly to a self-actinggrapple adapted to be used with a hoist, or the like, and whichautomatically opens and closes to clamp a log, or other load, uponmovement of the grapple, under control of the hoist operator, withoutthe need for stationing a man at the load, to assist in the clamping, orunclamping action.

It is a primary object of the invention to provide a grapple, forlifting logs, or other heavy loads, which is self-acting to clamp andunclamp without the need for manual assistance, the clamping andunclamping taking place automatically by relative movements of thedevice and the load under control of the hoist operator in lifting andlowering the grapple.

It is an important object of the invention to provide a grapple, havingthe above described characteristics, which saves manpower and therebyreduces operational costs.

It is another object of the invention to provide a grapple, having theabove described characteristics, which is of mechanical construction,designed toclamp and unclamp only when the grapple is moved in aselected direction and then in the opposite direction, wherebyaccidental operation is unlikely.

Yet another object is to provide an improved grapple having increasedsafety, due to avoidance of manual operation, and which preventsaccidental unclamping, or falling of the clamped loads, whereby injuryto persons, who would normally be stationed at the load to assist inclamping and unclamping, is eliminated.

A further object of the invention is to provide an automatic grapple,having the above described characteristics, so designed as to clamp andremain clamped to a load without danger of accidental release due toswinging of the load, or the striking of the load against other objects.

A still further object of the invention is to provide an automaticgrapple, having the above described characteristics, which is capable ofapplication in many industries in addition to the logging industry, andparticularly in industries involving the handling of loads withoutdirect or proximate contact of the loads with people, as for example, inraising and lowering of loads from and into water, and in handling loadsof dangerous nature.

Yet another object of the invention is to provide an automatic grapple,having the above described characteristics, which is of relativelysimple construction, yet strong and durable, easy to fabricate, and easyand economical to use.

The grapple device according to the present invention and which meetsthe above described objects, will be described in its form primarilyadapted for logging timer on the ground, or in water. It will beunderstood, however, that the grapple is adaptable to other uses, suchas for example, in retrieving sunken objects, boats, or the like, inclearing areas of obstructions, refuse, trash, or partly demolishedbuildings, and in handling dangerous or hazardous materials. It shouldbe clear, therefore, that the automatic grapple is capable of universalapplication.

The grapple according to the invention may be briefly described ascomprising a pair of pivoted tongs connected by links to a supportmember adapted to be raised or lowered by a hoist. The support member isprovided with a vertical, inner tube whose bore presents a guide pathfor movements of a ram connected to the pivot of the tongs and whichmovements clamp and unclamp the tongs. A trigger extends across saidpath and is connected by linkage to a pivoted latching element whichturns into said path to permit downward movement of the ram and clampingof said tongs. When the trigger is struck by the ram, the latchingelement is moved by the linking mechanism to a locking position acrossthe bore of the tube for cooperation with a locking element on the ramto hold the ram in elevated position and the tongs in open condition.Thus, the grapple may be lowered to engage the open tongs on a log, orother load, such engagement raising the ram to strike the trigger,causing the trigger linkage: to unlock the latching elements and movethe pivoted latching element out of said tube bore so that uponsubsequently lifting the grapple, the tongs and the ram are free todescendby gravity and clamp the log. When the grapple is subsequentlylifted, the log is lifted also and may be moved to any desired location.To release the log from the grapple, it is necessary to first lower thegrapple so that the log is deposited on a surface causing the ram toagain ride upwardly against the trigger. Actuation of the trigger by theram moves the pivoted latching element across the path of the ram sothat upon subsequent raising of the grapple, the ram is latched in itsraised position and as a result, the tongs are in their open conditionready to be moved to pick up another log.

With the above outline of the structure and mode of operation, it shouldbe clear that the grapple is automatically operated, first to clamp thetongs on the load, by a downward movement followed by upward movement.Unclamping is also performed by the same movements, first lowering thegrapple until shortly after the load rests on a surface, whereby to liftthe ram and open the tongs, and then raising the grapple to remove thesame from the load. The tongs are maintained in their open condition andwhen the grapple is lifted vertically. In this fashion, the grapple isclamped and unclamped automatically by a pair of opposite and sequentialmovements in the preselected vertical direction, ruling out accidentaluncoupling by movements in other directions, by swinging movements, orby striking the load, or the grapple, against other objects.

A grapple constructed as described Ihasmany advantages. Primary amongthese are the avoidance of need to position one or two men at the load,to assist in the clamping and unclamping of the load. The constructionof the grapple is such that once clamped it is virtually impossible tounclamp without following the above described sequence of movements.Accidental unclamping, therefore, cannot take place, yielding increasedsafety. the grapple may be made in any size to lift any load.

The novel features that are considered characteristic of the inventionare set forth with particularity in the appended claims. The invention,itself, however, both as to its organization and its method ofoperation, together with additional objects and advantages thereof, willbest be understood from the following description of a specificembodiment when read in connection with the accompanying drawings,wherein like reference characters indicate like parts throughout theseveral FIGS., and in which:

FIG. 1 is a front elevation of a grapple according to the invention withthe front cover wall removed and the tongs shown in open condition;

FIG. 2 is an elevational view looking from the right side of FIG. 1 andwith the cover of the device shown in phantom;

FIG. 3 is an enlarged fragmentary sectional view taken on line 3-3 ofFIG. 3, and looking in the direction of the arrows;

FIG. 4 is an elevational view taken from the left side of FIG. I withthe housing omitted and the tongs extended in their clamping condition;

FIG. Sis an elevation taken from the right side of FIG. 4;

FIG. 6 is a sectional view taken on line 66 of FIG. 4, and looking inthe direction ofthe arrows;

FIG. 7 is a fragmentary sectional view taken on line 7-7 of FIG. I, andlooking in the direction ofthe arrows;

FIG. 8 is a fragmentary sectional view taken on line 88 of FIG. 4, andlooking in the direction ofthe arrows;

FIG. 9 is an enlarged, fragmentary front elevation showing a portion ofthe link mechanism connecting the trigger to the latching element in itscondition as in FIG. 1 wherein the tongs are held in their opencondition;

FIG. 10 is an enlarged fragmentary view similar to FIG 9, but whereinthe tongs have moved to their closed condition; and

FIG. 11 is an enlarged fragmentary elevation similar to FIGS. 9 and 10,but wherein the tongs and said link mechanism are in an intermediateposition.

Referring now more particularly to the drawings, a preferred embodimentof the invention is shown as comprising a support member 10, a pair oftongs 12, a trigger 14, a ram 16, cooperating latching elements 18,20,FIG. 9, carried by said ram and support member, respectively, forholding the tongs open, and link mechanism 22 connecting said trigger toone latching element 20 and operative to move said latching element intoand out of latching engagement with the other element upon actuation bymovement of the trigger.

The support member 10 comprises an inverted U-shaped metal channel 24having depending platelike sides 26,28 connected by an upper bight 30.To each side 26,28 is hinged a pair of tongs, as later to be described,while integrally secured, or formed, with the bight 30, in the centerthereof, is an upstanding vertical tube 32 at whose upper end is fixed aloop 34 for reception of the chain, or hook, of a hoist, crane, or thelike, used in lifting the grapple. The vertical tube 32 is slotted inone of its walls'from its upper end downwardly as indicated at 36, FIGS.1 and 3, to receive and permit movement of the trigger 14. Another slot38, FIG. 7, is formed in an opposite wall near the bottom of the tube 10to permit passage of the latching element 20. A boxlike housing 40 isseated on the bight 30 of the U-shaped member 24 and secured thereto byany conventional means. Preferably, the housing is formed by a pair offrames, not shown, to which four sidewalls and a top wall are removablysecured by bolts, or the like, also not shown. The function of thehousing is to enclose the operating mechanism of the grapple and toprotect the same from entrance of moisture, dust, dirt, etc.

One pair ofcrossed tongs 12 formed of arcuate members 13 and 15 havinginwardly directed, barbed, lower ends 42, are rotatably secured at theircrossing point to a pivot bolt 44. The upper ends of the tongs arepivoted at 46,48 to the bottom ends of links 50,52, whose upper ends arepivotally secured by pivot bolt 54,56 to one flange 26 of the supportchannel 24. An identical pair of tongs 13,15 are secured in the samemanner to the opposite flange 28 of the support member 24. The tongs 13are connected together by one or more stiffeners 58 secured by welding,or otherwise, and the tongs 15 are likewise braced by stiffeners 58. Thepairs of tongs 13,15 thus described are light, strong and rigid, yetoperate in the same manner as if a single pair of heavy tongs wereutilized. The

upper end ofa bracing link 60 or stabilizer arm for tong 13 is pivotedat 62 to the support plate 26 at a point spaced on the opposite side ofram 16 from the link pivot 54, and at its lower end the bracing linkswivels on pivot 64 to the upper end of tong 13. A similar stabilizerarm 60 is correspondingly secured on the tong 15 of the other pair oftongs 13,15 to more uniformly distribute the weight of a load beinglifted and to smooth and better the clamping and lifting action.

The ram 16 as best seen in FIGS. 1, 3 and 6, comprises a vertical tube66 which slidably fits within the tube 32 of the support member 10.Internally, the tube 66 is braced by a pair of longitudinal strips 68,each of which is horizontally slotted at 70 to receive the pivot bolt 44of the pairs of tongs 12 with some play. Above the pivot slot 70 a stopflange 72 is integrally secured to each strip 68 to limit upwardmovement of the ram by engagement with the bottom of the support member30. The tubular portion'66 of the ram has a vertical slot 74 at itsupper end which aligns with the trigger-receiving slot 36 of the tubularportion 32 of the support 10, and in its opposite wall at the lower endhas a vertical slot 76, FIG. 7, to

the ram so as to cross an intermediate portion of the slot 74.

The roller 84 serves to strike the trigger and actuate the trigger linkmechanism, as will be hereinafter explained.

Secured to the support tube 10 by welding, or otherwise, are a pair ofspaced support brackets 86, FIGS. 1 and 3, to which are attached,-inconventional fashion, a pair of bearings 88, and a trigger shaft passesthrough aligned apertures in said support brackets and is journaled forrotation in said bearings. The trigger 14, FIGS. 1 and 6, comprises anarm extending through the aligned slots 36,74 in the support tube andram so that it crosses the bores of these elements. One end of thetrigger arm 14 is enlarged as a collar 92 fitting over the trigger shaft90 in the space between the support brackets 86. The collar and triggershaft are keyed together so that the trigger will pivot around the axisof the shaft from its normal position shown in FIGS. 1 and 6, to anupwardly inclined position when struck and so moved by the roller 82 inthe ram. During suchmovement the roller turns lessening the wear andshock.

The trigger shaft 90 extends beyond one of the journal blocks 88 and tothe protruding end is affixed the collar 94 of an actuating arm 96. Asbest seen in FIGS. 6 and 7, a second shaft, or latching shaft 98 issimilarly mounted for rotation in the bearings 100 secured by screws 102to a pair of mounting plates 104 on the opposite wall of the supporttube 32 and at a lower elevation. The latching shaft 98 passes throughaligned apertures 106 in said support plates and the latch 20 in theform of a bar, or finger, extends radially from a collar 108 which iskeyed at 110 to the latching shaft. The latch bar 20 extends through theslots 38,76 in the support tube and ram in one position to engage underthe latch bar 18 welded across the bore of the ram thus holds the ram upand the tong open. Latch shaft 98 will, upon turning, pivot the latchbar out of the support tube 32, permitting the ram to descend and thetongs to close.

On one protruding end of the latching shaft 98, FIG. 7, is keyed a crankarm 112 to whose end spaced from the shaft is a hooked, or otherwisesecured, one end ofa biasing spring 114, best seen in FIG. 4. The otherend of the biasing spring is secured in any conventional manner to a lug115 extending from a wall of the support tube 32. On the otherprotruding end of the latching shaft is keyed a collar 116 having aradial arm 118 and an outwardly bent axial leg, or dog 120. This legpasses through and rides in an arcuate slot 122 shaped as the segmentofa circle coaxial with shaft 98 and formed in a disc 124 which isrotatably journaled on the shaft 98. Outwardly of the disc 124 isprovided a cam 126 in the form of a radial protuberance on collar 128,FIG. 9, which is also keyed to shaft 8. To cooperate with cam 126, thedisc 124 carries a cam follower in the form of an arm 130 pivoted at 132near one edge of the disc and having a follower wheel 134 journaled atthe inner end of the follower arm, as best seen in FIGS. 9 and 10. Acoil spring 136 mounted between a lug 138 and the cam follower arm 130urges the follower wheel 134 against the cam 126. Pivotal movement ofthe cam follower arm is permitted about the axis ofpin 132, but islimited by stop arm 140 secured to the disc and riding in an arcuateslot 142 coaxial with the pivot 132.

The link mechanism 22 connected the trigger 14 to the latch element 20is completed by an actuator link 144 formed in two telescoping parts, asbest seen in FIGS. 1, 2 and 8. The bottom of the lower part 146 ispivotally connected at 148 to a point near the rim of the disc 124 andextends upwardly having an offset section 150 to permit space for thelatching shaft 98. The upper end of part 146 above section 150 is oftubular shape having a piston 152 riding in its bore. A piston rod 154extends trough an aperture 156 in the cap of the tubular portion, and anut 158 threaded on the piston rod 154 limits downward movement of thepiston, as viewed in FIG. 8, upward movement being limited by engagementof the piston 152 with the cap 160 threaded on the tubular portion. Thedescribed arrangement of piston 152 and associated parts yields a smallamount of play and adjustment thereof. The

upper end of the piston rod is pivoted by pin 162 to the free end 'ofthe trigger actuator arm 96. This arm is biased" downwardly by coilspring 164 hooked thereto and secured at its other end, in an convenientmanner, to a lug 166 on the wall of the tubular support 32. Coil spring164 biases the actuator arm to its down, or normal position, asillustrated in FIG. 1, which correspondingly positions the triggeracross the bore of the tubular support, as shown in the same Figure.

It will be apparent from close examination of FIGS. 9-H that in thenormal position of the trigger with the ram raised and the tongs in opencondition corresponding to FIG. 1 that the locking arm 20 extends partlyacross the bore ofthe tubular support and under the cooperating latchingbar, or element 18 which is welded, or otherwise suitably secured withinthe bore and to the walls of the ram. This prevents downward movement ofthe ram and closing of the tongs. In this condition, the actuator linkM6 is pivotally secured to the disc 12 at a location below and slightlyto the left of a vertical plane passing through the trigger shaft 126,so that upon actuation of the trigger lifting of ram 16 the actuator arm146 will lift and turn the disc 1416 clockwise, as indicated by thearrow in FIGS. 9 and III. This will cause the lower end of slot 122 toengage and turn the dog I20 pivoting the latch bar out of the bore ofthe ram into its unlatched condition shown in FIG. 6. FIG. 11 shows anintermediate position wherein the disc has turned partly. Since the camfollower ll34l is being carried by the disc in the same direction as thelatch 20 and the cam 126, the follower and cam will not change positionrelative to one another.

When the ram releases the trigger M and starts downwardly, pin 148 willstill be to the left of the vertical plane through the center oflatching shaft 93. As a result, spring 1641 will lower arms 96 and I46,the later turning the disc I24 counterclockwise and moving to theposition shown in FIG. 10. During this return slot 1122 does not engagedog 120 so that the latch bar 20 remains in its unlatched position. Thespring 114 previously described as being connected to the crank arm 112on the latching shaft is much stronger and in its FIG. 5 position exertsa much greater biasing force on the latching shaft than does the spring136 which biases the cam follower against the cam 126. Return rotationof the disc 124 wherein the cam follower and its spring oppose theaction of spring 114 will result in moving the cam follower 134 tooverride the cam and take position on the opposite side of the cam.Thus, the lock bar will remain in its unlocked position despite returnofthe disc.

A similar action occurs upon reverse movement of the lock bar 20 whenthe grapple is lowered and raised to release a load. In this instance,lifting of the ram and trigger through actuator link M6 first turns thedisc, as in FIG. 10, counterclockwise moving the lock bar 20 in the samedirection. Upon release of the trigger and downward movement of the ramthe disc will turn clockwise and return to its FIG. 9 position, the camfollower overriding the cam thus holding the latch bar 20 in its lockingposition. In this way, the cam and follower arm do not prevent themovement ofthe locking lug 20 to latching, or unlatching positions.However, once either of these movements is completed, the linkagemechanism 22 under the influence of the trigger actuator spring 164moves back toward its initial position corresponding to the normalposition of the trigger M, but the locking lug remains stationary.

The described structure operates in the following manner. Assuming thatthe parts are in their positions illustrated in FIG. 1 with the tongslocked in open condition, and a hoist, or crane, hooked to the loop 34,the hoist operator lowers the grapple to engage a log, or other load,disposed on the ground. When the upper surface of the log strikes thetongs just under their pivot pin 44 the tongs, pivot pin and ram 16 willelevate with respect to the support member lltl and the ram will slideupwardly in the bore of the tubular portion 32 of the support memberuntil the roller b2 contacts the trigger and moves it upwardly. Thetrigger and trigger shaft 90 will turn against the bias of spring 164causing the actuator arm 96 to rotate counterclockwise in FIG. 1. As aresult, the disc 24 will rotate clockwise from its FIG. 9 position andupon release of the trigger, will return to its FIG. position, aspreviously explained, moving the locking lug out of the bore of thetubular support 32. The hoist may then be operated to lift the grappleduring which movement the ram 16 will slide downwardly in the bore ofthe tubular support 32, and not being impeded or prevented by theunlatched lug 20, the tongs will move with the ram and by gravity toclosed position to clamp the log. Continued upward movement of thegrapple will, therefore, lift the log, or other load, from the ground,and the load then may be moved to any desired location. During suchmovement, the cam follower engages the upper side of the cam 126 in themanner shown in FIG. 1b, holding the latching element 20 out of the boreof the tubular support so as to free the same for subsequent upwardmovement of the ram within the support bore. During all lifting andtransporting movements of the grapple, the tongs will be in closedcondition, held and tightened therein by the weight of the load and willextend downwardly as shown in FIG. 5.

To unclamp the grapple from the load, it is merely necessary to againlower the grapple until the log is deposited on and touches the ground,or any surface intended to receive the same. If the grapple is thencontinued to be lowered a slight distance, the ram will slide upwardlyin the unimpeded bore of the tubular support and again strike and liftthe trigger, open ing the tongs to release the load. This movement ofthe trigger will elevate the actuator link arm 146, rotating the discK24 counterclockwise, as viewed in FIG. 10, and returning the lockingelement 20 to latching position as previously explained. Raising thegrapple will lower the ram in the bore of the tubular support away fromthe trigger until the latching bar 10 seats on latch element 20, holdingthe tongs open. The return movement of the disc 124 to its conditionshown in FIG. 9 has previously been explained. The log having beenreleased by initial opening of the tongs will not be reclamped by thetongs as the grapple is lifted further, and the grapple is then incondition to be applied to another log, the tongs being open and readyto repeat the clamping action described in the preceding paragraph.

It should be clear from the above that the described device isself-operating, clamping the load automatically by merely lowering thegrapple to engage the load, and subsequently raising the grapple. Thus,the clamping is accomplished by a sequence of two opposite movements inthe same vertical line. Correspondingly, to unclamp the load, thegrapple is again lowered vertically and upon triggering is then elevatedto remove the grapple from the load. Obviously, these simple movementscan be performed easily by the hoist, or crane operator without the needof assistance of another man, or men, positioned at the load, or thegrapple. Furthermore, the construction of the grapple is such that onceclamped, the load is safely held and carried by the hoist without dangerof unclamping. Even swinging movements and striking of either thegrapple or the load against a foreign object will not unclamp thegrapple, it being necessary to follow the described sequence ofmovements in a straight line first in one direction and then in theother direction to accomplish the unclamping. While the preferredembodiment entails vertical clamping and unclamping movements, thedevice may be modified to utilize movements in other directions.Although embodiment of the invention has been shown and described, it isobvious that many modifications thereof are possible. The invention,therefore, is not intended to be restricted to the exact showing of thedrawings and description thereof, but is considered to includereasonable and obvious equivalents.

We claim:

II. An automatic grapple device comprising a support member having meansfor attachment to a hoist, a pair of crossed, clamping tongs pivoted toone another at their crossing point, link means connecting the upperends of said tongs to the lower end of said support member, a ramconnected at one end to the pivot of said tongs, means on said supportmember defining a path for movement of said ram during closing andopening of said tongs, a trigger fixed to a pivot shaft and extendinginto said path to be struck by said ram, cooperating latching elementscarried by said ram and support member for holding said tongs open, andlink mechanism connecting said trigger to one of said latching elementsand operative to move said one latching element into and out of latchingengagement with the other latching element when actuated by movement ofthe trigger, said link mechanism comprising an actuator arm secured atone end to said pivot shaft, an actuator link pivotally secured at oneend to the other end of said actuator arm, a second shaft rigidlymounting said one latching element, and means connecting the other endof said actuator link to said second shaft operative to rotate said onelatching element to either latching or unlatching position, saidlast-named means including a disc rotatably mounted on the second shaftand pivotally connected to the actuator link, a slot in said disc shapedas a segment of a circle and coaxial with said second shaft, and an armsecured to said second shaft and having a dog extending into said slot,whereby turning of said disc by movement of said actuator arm results inturning of said second shaft through engagement of the ends of said discslot with the dog of said arm secured to the second shaft.

2. An automatic grapple device according to claim 1, wherein astabilizer arm pivotally connects the upper end of one ofsaid tongs tothe support means at a point spaced on the other side of the ram as theconnection of the corresponding link means supporting the same tong.

3. A grapple device according to claim 1, wherein said means defining apath for movement of said ram comprises a vertical tube in which saidram slides, said tube having slots in its wall permitting movements ofsaid trigger and said one latching element across the bore of the tube.

4. A grapple device according to claim 3, wherein said trigger ispositioned near the upper end of said tube and above said one latchingelement when the latter is disposed across the bore of the tube.

5. A grapple device according to claim 3, wherein said ram comprises ahollow tube having slots in its wall permitting movements of saidtrigger and said one latching element acrossthe bore of the ram.

6. A grapple device according to claim 5, wherein said ram is providedwith a trigger actuator in the form of a roller journaled in the wall ofthe tubular ram adjacent the upper one of said slots.

7. A grapple device according to claim 6, wherein said latching elementcarried by the ram comprises a latch bar secured in the bore of thetubular ram immediately above the lower one of said slots.

8. A grapple device according to claim 1, wherein said second shaft hasa cam affixed thereto, a cam follower being pivotally secured to saiddisc, biasing means urging said cam follower against said cam so as toprevent rotation of the second shaft, a second biasing means of greaterforce than said first biasing means connected at one end eccentric tosaid disc and fixed at the other end to said support member, wherebysaid second biasing means overcomes said first biasing means and causesthe cam follower to override the cam to retain the second shaft andconnected latching element in either latched or unlatched position onreturn movements of the trigger and disc.

9. A grapple device according to claim 8, wherein a third biasing meansis secured between said support member and said trigger actuator arm tooppose movement of the trigger and return the trigger to its normalposition across the bore of said path in said support member.

10. A grapple device according to claim 8, wherein said pivotalconnection of said actuator link to said disc is offcenter thereof andso arranged in relation to said cam follower and cam as to be beyondcenter of said second shaft in both the latching and unlatchingpositions thereof, whereby said discs and connected parts act as atoggle under force of said second biasing means to hold the saidlatching elements in both their latched and unlatched positions, andeach successive trigger actuation will through resulting movement ofsaid actuator link move said disc to rotate in the opposite directionfrom the precedin movement. I

11. A grapple evice according to claim 10, wherein said actuator link isformed of a pair of telescoping members having stop means limitingrelative motion therebetween in both directions, whereby the resultingmovements imparted to said discs and one latching element by theactuator link are accomplished with a snap action during a limitedportion of movement ofsaid trigger.

12. A grapple device according to claim 8, wherein said cam followercomprises a wheel rotatably mounted on an arm one end of which ispivoted to said disc, said first biasing means urging said arm in adirection to engage said wheel against said cam, said cam, arm and wheelbeing so arranged that turning of the second shaft in either directionas result of return force of said second biasing means will cause thecam to override the follower wheel depressing the follower arm againstthe urging of said first biasing means.

1. An automatic grapple device comprising a support member having meansfor attachment to a hoist, a pair of crossed, clamping tongs pivoted toone another at their crossing point, link means connecting the upperends of said tongs to the lower end of said support member, a ramconnected at one end to the pivot of said tongs, means on said supportmember defining a path for movement of said ram during closing andopening of said tongs, a trigger fixed to a pivot shaft and extendinginto said path to be struck by said ram, cooperating latching elementscarried by said ram and support member for holding said tongs open, andlink mechanism connecting said trigger to one of said latching elementsand operative to move said one latching element into and out of latchingengagement with the other latching element when actuated by movement ofthe trigger, said link mechanism comprising an actuator arm secured atone end to said pivot shaft, an actuator link pivotally secured at oneend to the other end of said actuator arm, a second shaft rigidlymounting said one latching element, and means connecting the other endof said actuator link to said second shaft operative to rotate said onelatching element to either latching or unlatching position, saidlast-named means including a disc rotatably mounted on the second shaftand pivotally connected to the actuator link, a slot in said disc shapedas a segment of a circle and coaxial with said second shaft, and an armsecured to said second shaft and having a dog extending into said slot,whereby turning of said disc by movement of said actuator arm results inTurning of said second shaft through engagement of the ends of said discslot with the dog of said arm secured to the second shaft.
 2. Anautomatic grapple device according to claim 1, wherein a stabilizer armpivotally connects the upper end of one of said tongs to the supportmeans at a point spaced on the other side of the ram as the connectionof the corresponding link means supporting the same tong.
 3. A grappledevice according to claim 1, wherein said means defining a path formovement of said ram comprises a vertical tube in which said ram slides,said tube having slots in its wall permitting movements of said triggerand said one latching element across the bore of the tube.
 4. A grappledevice according to claim 3, wherein said trigger is positioned near theupper end of said tube and above said one latching element when thelatter is disposed across the bore of the tube.
 5. A grapple deviceaccording to claim 3, wherein said ram comprises a hollow tube havingslots in its wall permitting movements of said trigger and said onelatching element across the bore of the ram.
 6. A grapple deviceaccording to claim 5, wherein said ram is provided with a triggeractuator in the form of a roller journaled in the wall of the tubularram adjacent the upper one of said slots.
 7. A grapple device accordingto claim 6, wherein said latching element carried by the ram comprises alatch bar secured in the bore of the tubular ram immediately above thelower one of said slots.
 8. A grapple device according to claim 1,wherein said second shaft has a cam affixed thereto, a cam followerbeing pivotally secured to said disc, biasing means urging said camfollower against said cam so as to prevent rotation of the second shaft,a second biasing means of greater force than said first biasing meansconnected at one end eccentric to said disc and fixed at the other endto said support member, whereby said second biasing means overcomes saidfirst biasing means and causes the cam follower to override the cam toretain the second shaft and connected latching element in either latchedor unlatched position on return movements of the trigger and disc.
 9. Agrapple device according to claim 8, wherein a third biasing means issecured between said support member and said trigger actuator arm tooppose movement of the trigger and return the trigger to its normalposition across the bore of said path in said support member.
 10. Agrapple device according to claim 8, wherein said pivotal connection ofsaid actuator link to said disc is offcenter thereof and so arranged inrelation to said cam follower and cam as to be beyond center of saidsecond shaft in both the latching and unlatching positions thereof,whereby said discs and connected parts act as a toggle under force ofsaid second biasing means to hold the said latching elements in boththeir latched and unlatched positions, and each successive triggeractuation will through resulting movement of said actuator link movesaid disc to rotate in the opposite direction from the precedingmovement.
 11. A grapple device according to claim 10, wherein saidactuator link is formed of a pair of telescoping members having stopmeans limiting relative motion therebetween in both directions, wherebythe resulting movements imparted to said discs and one latching elementby the actuator link are accomplished with a snap action during alimited portion of movement of said trigger.
 12. A grapple deviceaccording to claim 8, wherein said cam follower comprises a wheelrotatably mounted on an arm one end of which is pivoted to said disc,said first biasing means urging said arm in a direction to engage saidwheel against said cam, said cam, arm and wheel being so arranged thatturning of the second shaft in either direction as result of returnforce of said second biasing means will cause the cam to override thefollower wheel depressing the follower arm against the urging of saidfirst biasing means.